Continuously operating paper-treating machines, in particular rotating-roll machines, are loaded with paper strips that are wound off supply rolls. When one roll is depleted, it is replaced by a new roll without stopping the treatment machine. Roll changers are known that effect a so-called “on-the-fly roll change.” This is done by providing an adhesive band on the leading end of a fresh roll waiting for use. The new roll is rotated and brought to a peripheral speed that is synchronized with that of the almost empty roll. At the appropriate time the paper strip is pressed against the new roll so as to contact the adhesive band. In this manner the leading end of the new strip is adhered to the running-out strip. The running-out strip is cut off after a slight delay. The delay is necessitated by the inertia of the cutter and the cycling time of the control system. This leaves a so-called flap that projects from the adhesive band and that has a length determined by the length of the delay. The length of the flap is a function of the strip speed as well as of the delay time. If for example the delay is 10 ms and the strip speed is 15 m/s, the flap is 150 mm long.
Practice has shown that such flaps can cause problems in the downstream treatment stations. German patent document 198 04 415, which the instant invention is based on, describes a method that manages to cut the flap to a harmless residue of at most several millimeters long. It also describes several systems for carrying out the method with this known method the glued-together paper strips are deflected about an arc having a center of curvature on the face opposite the flap. When the flap moves through the arc it is swung out by centrifugal force and cut by a blade that is closely spaced from the strip. The separating effect of the centrifugal force can be augmented by an air blast that is directed between the paper strip and the flap parallel to the travel direction of the strip. In order to ensure that the cut is made, in one embodiment a separating device, e.g. a suction drum or belt, is set at a spacing of 20 to 60 mm from the paper strip upstream of the blade and is driven at a speed that is greater than the travel speed of the strip. The flap that is separated by the air blast and centrifugal force from the strip is held by the suction of the separating device, accelerated by friction, and thus fed to the blade.